Lubricants



July 311 1945' s. E. JOLLY LUBRICANT original Filed June 25, 1943 Patented July 31, 1945 UNITED sTATEs PATENT OFFICE LUBRICANTS Samuel Edward Jolly, Prospect Parla, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Original application June 25, 1943, Serial No. 492,227. Divided and this application October 28, 1943, Serial No. 508,061

4 Claims.

, acids.

Sulfurized esters or glycerides of fatty acids have been used in various special lubricants. However, lubricants which contain esters or glycerides may undergo hydrolysis or become rancid, thereby developing an acidity which imparts corrosive properties to the lubricant. Hydrolysis is also objectionable for the reason that many l`ubricants, particularly soluble oils and greases, for best performance, should be slightly alkaline. Sulfurized nitriles, on' the other hand, do not undergo hydrolysis under conditions encountered in service and therefore are of particular utility in the manufacture of special lubricants. The preparation of such Sulfurized nitriles soliible in,

and suitable as additives to, lubricants, presents,

however, serious problems which I have succeeded in solving. A full disclosure of my invention therefore necessitates a detailed description of the method by which sulfirized nitriles, suitable for use as additions to lu'iricants and for imparting to lubricants the qualitiesI which it is desired they shall have, should be prepared; and

the following description is therefore mainly addressed to such method. I should here state that it should be understood that I do not claim to be the first to, in any manner, react fatty acidnitriles with sulfur or sulfur compounds, or to be the first to add such reacted nitriles to lubricants to produce extreme pressure lubricants. Thus,

Ralston U. S. Patents 2,125,853 and 2,141,142 dis".

close the preparation of reaction products of nitriles with sulfur monochloride cr with sulfur monochloride and sulfur and their use in extreme pressure lubricants. These products, however, contain sulfur and chlorine in chemical combination. It is a characteristic feature of, h

my improved lubricant that it contains combined sulfurizing step of my process.

sulfur but is free of chlorine or combined chlorine.

My method of producing such an improved sul furized nitrile involves its preparation from starting materials containing higher molecular weight organic acids, such as fatty acids and rosin acids, in two major steps comprising conversion ofr the acids to nitriles and the sulfurization of the nitriles.

Numerous methods of converting fatty acids into nitriles are known, some of which are of only academic interest while others have shown commercial value. In the latter methods the conversion generally has been effected by causing the fatty acids and ammonia to react in either liquid or vapor phase according to' thefollowing Ralston et al. U. S. Patent 2,061,314 discloses a method of effecting these reactions in liquid phase, and Potts et al. U. S. Patent 2,314,894 discloses an improved method comprising both liquid and vapor phase reactions. Methods wherein these reactions have been carried out wholly in vapor phase in many cases have proved unsatisfactory due to decomposition of the fatty acids on vaporization. Such of the known methods as prevent decomposition of the fatty acids on vaporization and are otherwise of commercial value may be used, with some starting materials, to form nitriles that may be subjected to the However, with certain preferred starting material, these methods are not altogether satisfactory, as is more fully explained hereinafter; and my process preferably involves, as a first major step. an improved method for converting organic acids to nitriles which, when Sulfurized in accordance with the second step of my process. will produce a Sulfurized nitrile whose addition to lubricating oils or greases vwill reliably impart to them the qualities sought.

As starting materials for conversion to nitriles I may utilize such materials as stearic acid, oleic acid, lard oil acids and other fatty acids of animal, vegetable or marine origin which have at least ten carbon atoms. I have found that talll whichis a mixture of fatty Land rosin acids is also preferred because of its ready availability and low cfost. However, whether starting with talloil, or any other organic acid having atleast carbon atoms vand selected from the group consisting of fatty acids and rosln acids, I first form nitriles under conditions sucir that no sub- 10 s'tantial amount of reaction products boiling above the boiling range 'of the starting acids are formed, and then react the so-formed nitriles with free sulfur at an elevated temperature for a length of time sulcient to give. a homogeneous prodl5 uct .but insufficient to cause the formation of mineral oil-insoluble'products. I have discov. ered that nitriles which a'rehigher boiling than the starting acids from which theyf'were prepared, apparently due to polymerization during 2()l their format on, on sulfurizing yield products.' `which are vsu stantially oil-insoluble and therefore unsuitable in the present application. Further, I have discovered that nitriles, even though they may be of suitable `boiling range, likewise yield substantially oil-insoluble products on sulfurization unless the reaction between the nitriles..

and` sulfur is carried out in relatively short time. When such starting materials asj stearic acid,

oleic acid or lard oil acidsar'e used, various here'- 30 toforeknown methods'oi preparing theA nitriles are suitable, as'hereinbefore stated. -Howeven when, as is preferred, talloil, is used as'the starting material` these known methods generally give a product containing a cohsiderable'proportion 35 of nitriles which boil higher than the boiling range of th talloil\ and which on sulfurization form undesirable oil-insoluble products. In order- Ito use nitriles preparedfrom talloll according to methods heretofore known, it usually is necessary 40 toiremove the high boiling material, for instance by distillation, thus sacrificing yield of nitriles in A order to obtain the desired quality. .I have discovered that nitriles of suitable boilingrange may be prepared 'from talloil in accordance with the 45 reactions listed above by contacting the talloil in liquid phase and at elevated temperature withA ammonia vapor under such conditions that the time of contact isA relatively short, for instance not more than say twenty minutes and p'refer-` fr0 ably le's's'if possible. This causes lthe Adesired reactions to proceed without allowing the reactions that result in the formation of high boiling nitriles to take place to a substantial extent.

In order to obtain the desired high yield in such 5 suitable 'means of effecting an intimate but short- 60 timed contact: Further-(it is desirable to' c'arry out the reaction in the presence of `a dehydrating catalystv such as alumina or' silica. gel in order to accelerate the reaction. anda preferable means of accomplishing this is by employing catalyst as N the packing material for the contact column.

Thus my preferred method of preparing nitriles comprises continuously'leeding heated talloil to the top of a contact co umn packed with a dehydrating catalyst.` con inuouslypassing ammonia vapor through the column and allowing l the talloil to trickle over the catalyst and flow by gravity to the base of the column, thereby effecting an intimate contact of short duration between the liquid and vapor phases. l

asentar requiring a longer time` of contact 'with a resultant increase in the proportion of undesirable highboiling material formed. Temperatures above 375 C. tend tocause decreased yield of desirable nitriles, possibly by causing cracking of` the reperhaps an .unfavorable displacement in the equilibrium of the first step of reaction illustrated by Equation l, supra.

' Sulfurizlation of the nitriles is accomplished by reacting 'elemental sulfur with the nitriles and may be lcarried out in either batch or continuous manner. There are two critical. interrelated factemperature and the time'of reaction. In or'der to initiate the reaction between nitriles and sulfur the temperature should not be much below 190 C. 'Ihis minimum temperature is rather critical. Thus a temperature of 180 C., while not greatly below 190 C., gives an exceedingly slow rate of reaction; A product produced by a slow rate of reaction containsinsoluble material varying from small to large amounts dependent withv such a product, even though the amount of insoluble material contained therein may be i comparatively small, precipitates, after a few days of' aging, a black sludge, as hereinafter fully explained. The product that I produce should contain no more than a trace of insoluble material. This requires, in the sulfurizlngstep as above stated, a short time of reaction,.and this short time of reaction in turn requires a minimum temperature which more nearly approachesl C. than C. and therefore is not substantially below C. After the reaction has been iniy tiated by raising thetemperature of a mixture of nitriles and sulfur to,19l)"C., there ,is a tendency toward further-increase in temperature due to the exothermicnature of the-reaction. This is not objectionable provided theprocessing equipment is properly designed for handling the materials at higher temperature with safety, and provided. of course.. that the `temperature is not allowed to rise so high as to eiTect any substantial cracking of thernitriles. The necessary teml vperature factor is, therefore, highly flexible so far as concerns itsy upper limit,I but critical in that it is necessary that it should be within a zone having the specified lower limit. Operation under sucha temperature allows the reaction to proceed only so long as to rgivea product that will be homogeneous at ordinary temperatures, but

products; The time of reaction also depends on the proportion of sulfur used. The lower the proportion of sulfur and the higher the reactionA temperature, the shorter is the required reaction time. At a temperature of about 190-200" C., it is desirable that the reaction time be not over about 15 minutes, although somewhat longer reaction times may not be too unsatisfactory for practical operation. n

In the accompanying single sheet of drawing there is shown schematically a preferred form of apparatus for practicing the above described process, which, for purposes of illustration, is described in connection with the processing of tali- 6 oil, but which islalso suitable for the processing tors involved inv this step.' namely, the reaction upon the reaction time; and filtered oil, blended` not so long as to cause formation of oil-insolubleA of other charge stocks such as stearic acid, oleic acid and lard oil acids. i Y

As shown inthe drawing, talloil, which may be either crude or refined and which usually will conform to the following specifications:

Saponification No 17o-185 Acid No i60-180 Iodine No 90-130 Fatty acids per cent.- J44-60 Rosin acids, calculated as abietic acid do 34-47 Sterols, higher alcohols, hydrocarbons,.

etc do 6-10 Moisture do-- 0.1-0.3 Ash do 0.1

is charged to the appartus by means of charge pump 2. The talloil passes through preheater 3,

perature is reduced preferably to a level such that the temperature within sulfurizing column I1 will be about i90-200 C., whence it passes to the base of sulfurizing column I1. Sulfur also `is added near the base of the column in proportion Contact column 4 is packed with a granular dehydrating catalyst I such as alumina, the catalyst being supported at a point above the bottom of the column by a suitable catalyst support 9 such as a wire grille. The entering. talloil preferably is distributed evenly on the alumina near the top of contact column 4 by means of a distributar 9 which may be of any suitable form. Ammonia vapor, preferably anhydrous, is preheated to a temperature of 325-375" C. in preheater I0 and is passed into the column suitably I. at a. point just below catalyst support 8. The

talloil flows down the column as a thin fllm on the surfaces of the catalyst and countercurrently to the ascending ammonia vapor stream, thereby intimately commingling with the ammonia. At

the top of contact column 4 there is provided vapor outlet line II through which eiiluent vapors, comprising excess ammonia, water formed. in the reaction and any low boiling organic materials present or formed during the reaction, are withdrawn. 'I'hese vapors preferably are passed through apparatus for separatelyrecovering ammonia and any low boiling organic materials, which is not shown in the drawing since apparatus suitable for accomplishing this is well known and forms no part of the present invention. The' liquid stream ows by gravity from the catalyst zone and collects in the base of the column, and sight gauge I2 is provided as an vaid in maintaining a low liquid level therein. The liquid level is regulated by means of valve I3 in outlet line I4 or by varying the speed of pump I5. The reaction product which is withdrawn from/the' base of the column by means of pump I5 consists predominately of nitriles having a boiling range not higher than that of the talloil charge stock, provided the contact column is of suitable height and proper operating conditions are maintained.

Contact column 4 obviously should be insulated or provided with suitable heating means for maintaining a temperature of 325-375 C.

"On continued operation the catalyst 1 in contact column 4 usually will decrease in activity due to deposition of small amounts of gums,v

desired for reaction with the nitriles. As illustrated in the drawing, this may be done by feeding finely divided sulfur from hopper I8 to the column by means of screw conveyor I9. Sulfurizing column I'I is provided with a stirrer driven by electric motor 20 and comprising a centrally located shaft along which is attached'in suitable space arrangement a, plurality of blades or other means for dispersing the sulfur and effecting intimate contact between the nitriles and sulfur as the mixture flows up the column. It is desirable that sulfurizing column I1 be of sufciently small diameter so that the mixing effected by the stirrer is mainly lateral without a substantial amount f vertical mixing in order that a reasonably definite continuous flow of the mixture up the column obtains. Sulfurizing column I1 also is provided with a ,plurality of outlet lines (2 I--a, b, c, d, e, f) vertically spaced along its upper section, all provided with valves by means of which the level of withdrawal ,of reaction products is controlled. With this arrangement the time of reaction between -the nitriles and sulfur depends on the rate of ow, the diameter of the sulfurizing column and the level from which the reaction mixture is withdrawn; thus for a given rate of charge to the process the reaction time may be varied as desired by varying the level of withdrawal. In order to maintain the desired short reaction time for various rates of flow, one of the lower levels, for instance line (ZI-a), would be used for a slow rate of flow while a higher level,

for instance line (2l-e), would be used for a- Obviously the equipment must beA faster rate. properly designed to allow suitable adjustment for any charge rate that may be employed.

The sulfurized nitriles from column I1 i'low through cooler 22 and thence may be sent to storage or directly to a blending tank as base Present gtg method (prolonged (short-timed baten treatment) ment) Reaction temperature 260-290 C-. S40-375 C.

Approximatetime of contact. 10 min.

Acid number of talloil charge 175.

Acid number of product 4.7.

Per cent. of. product having suitable boiling range.

Yield of nitriles of suitable boiling 62- 89.

range, calcd. as per cent. of maxlmum possible yield As indicated byY the and numbers of the products,

the method described above.

approximately the same proportion of the charge was converted to nitriles in each case. However, with the known method only 55 per cent. of. the product was of suitable boiling range (i. e. not higher than the boiling range of the talloil), whereas 92 per cent. of the product prepared according to my improved method was of'suitable boiling range. Thus the latter product contained only 8 per cent. of nitriles of higher boiling range-an amount insuflicient to cause the product on sulfurization to yield oil-insoluble material- While the product of the known method contained 45 per cent. of such higher boiling nitriles which rendered it unsuitable for preparation of sulfurized products for addition to -lubricants. i

In the step of sulfurizing the nitriles, the importance of a short reaction time may be demonstrated by lsulfurizing samples of the nitriles for -various lengths. of time, mixing the sulfurized samples with mineral oil and noting the amounts of insoluble material, iiltering the blends to remove the insoluble material, then allowing the filtered blends to age at a low temperature and noting any further formation of insoluble material. The data given below are illustrative of experiments of this type which have been made with nitriles prepared from talloil according to In each of these experiments 25 parts of sulfur were reacted with 75 parts of nitriles at a temperature of 19o-200 C., and 10 parts of the resulting sulfurized nitriles were blended with 90 parts of mineral oil.l

Reaction Amount of insoluble l Observations on filtered blend time, material in uniilminutes tered blend after gmg at 6 C' 5 'I race No separation after 30 days of agm l 35 Small amount L-. Preciptateafterdaysoi'aging;

bk sludge after 8 days of a Considerable amount'` Preciplitate afterdays of aging;

aging.

This` tabulation indicates that a reaction time less than 35 minutes is required in order to produce stable products.

' base stock to 90 parts of'oil.

black sludge after 7 days of While the invention herein claimed is a lubricant containing a majorproportion of mineral oil and a minor proportion of oil soluble sulfurrine and formed by reacting sulfur at a temperature not substantially less than C. and under substantially non-polymerizing conditions with nitriles of organic acids having at least 10 carbon atoms and selected from the group consisting of fatty acids and rosin acids, said lubricant being characterized by stability against settlement of sludge after a comparatively long period of aging.

2. A lubricant comprising a major proportion.

of mineral oil and a minor proportion of oil-soluble sulfurized nitriles free of combined chlorine and formed by reacting-sulfur with nitriles of talloil at a temperature not substantially less than 190 C. and under substantially non-polymerizing conditions, said lubricant being characterized by stability against settlement of sludge after a comparatively long period of aging. y

3. A lubricant comprising a major proportion of mineral oil and a minor proportion of oil-soluble sulfurized nitriles free of combined chlorine and formed by reacting sulfur at a temperature not substantially less than 190 C. and under substantially non-polymerizing conditions with nitriles of organic acids having at least 10 carbon 'l atoms and selected from the group consisting of fatty acids and rosin acids and no substantial proportion of which boils above thel end boiling point of such acids, said lubricant being characterized by stability against settlement of sludge after a comparatively long period of aging.

4. A lubricant comprisinga major proportion of mineral oil and a minor proportion v'of oilsoluble sulfurized nitriles free of combined chlorine and formed by reacting sulfur, at a temperature not less than 190 C. and under substantially non-polymerizing conditions, with nitriles of talloil no substantial proportion of which boils above the end point of talloil, said lubricant being characterized by stability against settlement of sludge after a comparatively long period of aging.

l' SAMUEL EDWARD JOLLY. 

